1. Field
Apparatuses consistent with embodiments relate to an image projection apparatus, and more particularly to an image projection apparatus provided with a pair of prisms for guiding illumination light to an image forming unit (for example, a digital micromirror device (DMD) panel).
2. Description of the Related Art
An image projection apparatus is an apparatus that converts illumination light generated in an illumination unit into an image having image information and performs extended projection of the image onto a screen.
One type of image projection apparatus includes an illumination unit generating illumination light, a light uniformity unit (for example, a light tunnel or a fly eye lens) making the illumination light uniform, relay lenses adjusting an illumination area of the uniform illumination light with an appropriate size, a pair of prisms changing a path of the illumination light having passed through the relay lenses, an image forming unit (for example, a DMD panel) converting the illumination light that is guided by the prisms into an image, and a projection lens unit performing extended projection of the image onto a screen.
The pair of prisms include a first prism performing total reflection of the illumination light to the image forming unit, and a second prism guiding the image that is formed by the image forming unit to the projection lens unit. Here, the first prism has a total reflection surface, but the second prism does not have the total reflection surface. This feature is in distinction to the features of the embodiments to be described later.
In the above-described type of image projection apparatus, the illumination unit, the light uniformity unit, and the relay lenses are substantially arranged in a line along the length direction of the image projection apparatus. In the case of such an image projection apparatus, the number of components arranged along the length direction is relatively large, and thus it is not easy to design the image projection apparatus having a reduced length direction. Accordingly, such a type of image projection apparatus is unfit for being applied to a mobile phone or a pico projector that requires miniaturization design.